EFF:

If a consumer chooses to use it, the new "Search Across Computers" feature will store copies of the user’s Word documents, PDFs, spreadsheets and other text-based documents on Google’s own servers, to enable searching from any one of the user’s computers…

Google will have copies of your tax returns, love letters, business records, financial and medical files

Seems like being able to search your computer from any computer is a pointless feature anyway. Certainly if it means giving Google a copy of your hard drive.